There are many known bag machines. One style is a rotary drum machine. Rotary drum machines are well known, and a detailed description may be found in U.S. Pat. Nos. 7,445,590, 6,117,058, 4,934,993, 5,518,559, 5,587,032 and 4,642,084 (each of which is hereby incorporated by reference).
A detailed description of the operation of rotary bag machines may be found in the patents above, but their general operation may be seen with respect to the Figures of U.S. Pat. No. 6,117,058. The prior art rotary bag machine continuously processes a film/web using a dancer assembly, a pair of drum-in rolls, a sealing drum 208, a pair of drum-out rolls, a sealing blanket, a pair of knife-in rolls, a knife (which could be any other web processing device such as a perforator, knife, die cutter, punching station, or folding station), a pair of knife-out rolls, and a controller. Input section, as used herein, includes the portion of a bag machine where the web is received, such as an unwind and a dancer assembly. Output section, as used herein, includes assemblies that act on a web downstream of the seals being formed, such as perforators, winders, folders, etc.
The web is provided through the dancer assembly to the drum. The drum includes a plurality of seal bars. The seals bars are heated and create the seals forming the bags from the web. The web is held against the drum (and the seals bars) by a Teflon® coated blanket. The distance between seals created by the drum is related to the bag length (for bags formed end to end) or the bag width (for bags formed by making side seals). End to end bags are formed with one seal from the drum, and side to side bags are formed with a pair of seals. The drum diameter may be adjusted and/or less than all of the seal bars turned on to determine the distance between seals, and hence bag size. The drum diameter is adjusted using threaded rods. The prior art of FIG. 1 provides that after the web leaves the drum it is directed to the rotary knife which creates a perforation between bags, or could separate adjoining bags. U.S. Pat. No. 7,445,590 teaches to make the perforation on the drum.
Prior art machines typically included discrete input, sealing and output sections. Each discrete section was supported by a frame dedicated to that section. Frames were typically painted or otherwise coated, and could be sections bolted together, tubular steel, etc. Finish coatings have included primer, paint, nickel, zinc, chrome, or the like. Each section could be 15-20 feet or more in length. Because of the size of each section, frames were typically too large to be dipped for galvanizing.
Bag machines often include a downstream winder. Prior art winders are described in U.S. Pat. Nos. 6,186,436, 5,899,403 and 7,578,779 and US Patent Publication 20070045463, each of which is hereby incorporated by reference. Prior art winders often include three spindles mounted on a turret. One turret was in a transfer or initial wind position where the film is initially wound onto the turret, a winding position where most of winding is performed, and a push off position. The winding position provides for center and surface wind. The turret rotates and spindles are moved to each position. Three spindles are needed to provide the desired cycle rate and machine speed. The push off position is above the transfer and winding positions, which can result in a removed roll affecting the winding of a subsequent roll if the removed roll falls to the floor. The wound roll of bags is removed from the spindle. Prior art spindles can be tapered, and/or have air flowing through holes in the surface to facilitate removal.
A method and machine for making bags that provides a simple, compact design is desired. The machine preferable includes the input, drum and output section supported by a single common frame. The drum section preferably includes an adjustable drum, that is able to be economically manufactured. The output section preferably includes a winder that has a turret with multiple spindles, including a position for removing wound rolls that allows for rolls to be removed without interfering with the winding process. Winding is preferably performed with center and surface winding for much of the roll. The spindles preferably have a design that allows for easy removal of wound rolls.